I was looking for a robust keypad. Whilst searching I discovered the Storm 720 4 x 4 keypad, which is a very solid and durable keypad. (And yes, expensive too.)
However, I couldn't find any support how to connect this to an I2C interface. (I am using the Waveshare PCF874.)
I did find a datasheet on the Storm.uk site for this stout keypad, so after some fiddling I came to the next schematic.
On the backside of the Storm keypad pins are numbered from left to right from 8 to 1. When you turn the waveshare board with the four connecting pins facing to the left hand side, the yellow keypad pins also are numbered from left to right. So 8 left and 1 right. Then the pins should be connected like shown in the image.
